Patent GB-391135-A (GB)
Title: Improvements in or relating to electric relays and to their use in electric protective or other systems
IPC: H02H7/26
Filed: 1931-10-15
Abstract: 391,135. Protective cutout arrangements; electromagnetic switches. REYROLLE & CO., Ltd., A., Hebburn-on-Tyne, and LEBEN, H., 8, Queen's Walk, Harrow, Middlesex. Oct. 15, 1931, No. 28726. [Class 38 (v).] In a protective arrangement for a sectionalized power circuit in which the trip circuit of a circuit-breaker B, Fig. 5, at each end of the section is controlled by a tripping relay device D<22>, D<23> energized from the power circuit at the adjacent end, and operative to effect tripping upon excess current unless prevented by stabilizing devices C<15>, C<16>, c<15>, c<16>, responsive to the relative directions of power flow at the two ends, each tripping relay device comprises one or more relays each having two sequentially operated sets of contacts, and means whereby a lower current setting is obtained for operation of one set of contacts than for operation of the -other set of contacts, the higher current setting contacts D<25> controlling the adjacent trip circuit, whilst the lower current setting contacts D<24> prepare circuits for permitting the direction responsive devices to become effective. The protective arrangement shown in Fig. 5 is of the general kind described in Specification 314,778, [Class 38 (v), Electric switches &c.], and in the event of a fault in the section A<1>, A<2>, A<3> the tripping relay devices D<22>, D<23> and d<22>, d<23> at both ends will operate whilst the stabilizing devices C<15>, C<16>, C<15>, C<16> will remain inoperative. The operation of the tripping devices will energize auxiliary tripping relays Y, y, and the circuit-breakers B, b at each end will be tripped by the energization of their trip coils over contacts of associated timelag relays Z, z. In the event of a heavy straight-through current, the tripping devices D<22>, D<23>, d<22>, d<23>, and the stabilizing device c<15>, c<16> at the remote end operate, whereupon an auxiliary stabilizing relay l at the remote end is energized over the contacts of the stabilizing device c<15>, c<16> and the low current contacts d<24> of at least one of the relays of the tripping device d<22>, d<23>. The relay l opens contacts j<10> in the circuit of the relay z and thus prevents tripping of the circuit-breaker b and also connects a battery j<4> to pilot wires H<13>, H<14>, so that upon closure of the high current contacts of the tripping device D<22>, D<23>, and the consequent response of the relay Y, a lock-out relay W is energized from the pilot wires to open the circuit of the relay Z and prevent tripping of the circuit-breaker B. The stabilizing current signals may be communicated by high frequency carrier currents superimposed on the main conductors. Figs. 3 and 4 show a suitable construction of double-current setting relay for the tripping relay devices D<22>, D<23>, d<22>, d<23>. With a certain current passing through coils 20, 21, an armature 30 is attracted and closes contacts 48, 49, and when a certain higher current passes the armature 30, which now works against a spring 40, is still more attracted, and closes contacts 50, 51. The two current settings are independently adjustable by means of a plug 27 cutting in or out turns of the coil 20, and a nut 41 for adjusting the tension of the springs 40. In another suitable construction the first current setting is adjusted by a cam which varies the initial position of the armature. The relay may operate at its first current setting to open additional contacts, as well as to close the contacts 48, 49.